Mechanical Test Study Of Fractured Coal Rock Mass Under Cyclic Loading

In this paper,Rock is a basic discontinuous medium existing in nature in large quantities.Its structure is usually complex and uneven,and it often shows different mechanical properties due to different regions.But there are a lot of cracks and holes in it.Therefore,under the common disturbance of various geological activities,artificial mining and other factors,it is of great significance to explore the law of outward propagation and expansion of rock internal fractures and the causes of rock mass instability and deformation and failure for practical engineering application.Through uniaxial load,cyclic loading and unloading and other related basic mechanical tests,this paper analyzes the main mechanical properties of different specimens and their deformation and failure laws.The main conclusions are as follows:(1)determine the wave velocity,mass and other physical parameters of the specimen.Uniaxial compression test was carried out with YAW-3000 testing machine,and the parameters of static mechanical properties were obtained.The uniaxial compressive strength and elastic modulus of coal-rock mass are obviously smaller than that of mortar monomer,but its compressive strength is close to that of coal monomer.(2)under the action of cyclic load,the prefabricated crack has obvious influence on its mechanical properties,and its compressive strength is less than that of the specimen without crack.In the initial stage of cyclic load,the overall change degree of the specimen axial stress-strain curve is small,but it will affect the peak load intensity of the specimen to some extent.(3)the strength of the coal and rock assemblages and fissure Angle,inclination Angle,the greater the damage to the starting position of the moving closer to reshape the coal,the smaller the Angle of coal and rock damage injunction near the fracture position,and compare the two kinds of specimen failure pattern under different loading modes,uniaxial test specimen damage in shear failure as the main form,but also accompanied by tensile failure.(4)the initial failure location of fracture specimens of coal and rock mass with different inclinations is different.The larger the inclination,the more inclined the failure location is to be in the single part of coal.The fracture Angle affects the location where the failure occurs.When the inclination Angle is 900,the overall morphology of the mortar part of the coal-rock mass specimen remains relatively intact after failure.(5)the process of energy absorption,transfer and dissipation during the deformation and failure of the specimen is analyzed.Tie proportion of dlssipated energy is similar to the inverse function between cyclic loading and unloading.In the initial stage of cyclic loading,the higher the initial load is,the faster the propmrtion will change.The larger the amplitude is,the larger the proportion of dissipated energy will be.Figure[37]table[6]parameter[90]...